Flexible borehole liners may be installed in vertical or horizontal boreholes, pipes, ducts, and the like, for a variety of applications. One application installs liners with instruments in vertical or horizontal holes for the purpose of making measurements. Another application uses liners to line and support boreholes during horizontal drilling operations. A third application installs liners in sewers and other piping to renew and/or seal internal surfaces.
In drilling boreholes for emplacement of measurement or sampling devices, the common practice is to install the desired device in the borehole and then to seal the hole with a grouted liner to fill the entire hole with a sealing material. U.S. Pat. No. 5,176,207, issued Jan. 5, 1993, to Keller, teaches the use of a flexible tubular member to both seal and support a borehole and to carry instruments into a borehole as the flexible member is everted into the borehole. Instrumentation and sampling devices can then be placed directly in contact with the surrounding structure.
The flexible liners are normally installed from the interior of a pressure canister into the hole. The pressure canister contains the liner and the fluid pressure used to evert the liner into the hole. For very deep holes, the necessary liner volume becomes very large and requires the construction of a prohibitively large and expensive pressure canister from which to deploy the liner.
This problem is addressed in U.S. Pat. No. 5,154,936; 5,167,901; and 5,597,353, which provide a sphincter-like feed-through to deploy a liner. The sphincter feed-through is not well suited to install essentially flat and relatively fragile liners with attached instruments, or to seal about very small objects passing through a large sphincter. In some applications, the liner is deployed directly from a tension control device, which operates on a flattened liner. An attached cord for control of the everting liner often follows the liner. It is difficult for the sphincter device to seal about such cords.
Various objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.